1. Technical Field of the Invention
This invention relates to a system and method for determining the characteristics of value add network services (VANs), including those of a frame relay (FR) network.
2. Background Art
Frame relay (FR) networks are set up by providers of value add network services and also by private companies. The objective is to provide quality service at attractive prices. FR is a “layer 2” protocol that can serve as a shared, underlying transport medium for one or more higher layer protocols, such as TCP and SNA.
Because of frame relay assignment of virtual circuits across a wide area network, a single connection into the network can serve to connect to many other locations, thereby providing secure, low cost, high performance connectivity. This is a hallmark of frame relay use by value add network (VAN) customers; for example, connecting a data center via a medium speed link (e.g., 256 Kbps) to a FR cloud (containing T1 links) and connecting many branch offices to the FR cloud over slow links (e.g., 56 Kbps), allowing any-to-any connectivity.
In order to protect its wide area network (WAN), a FR VAN supplier will provide a guaranteed level of service, referred to as a committed information rate (CIR, or “green” frames), a best-effort, burst excess (Be) level of service (between CIR and Be, or “yellow” frames), and an automatic discard level (above CIR+Be, or “red” frames).
A VAN supplier charges a customer more for a higher level of service (more green frames), and less for a lower level of service (more yellow and red frames). This enables users to tailor their costs and service to the amount of traffic they need to transmit.
Heretofore, users paying for value add network services, such as those of a frame relay service, have had no way of checking to determine whether or not they are receiving the level of service for which they are paying. In fact, suppliers of value add network services (VANs) frequently are not able to describe to users how the frame relay parameters are actually set for the customer. Consequently, there is a need in the art for a test method that can provide this information both to users and to suppliers of frame relay (FR) services.
Heretofore, assembling a network view that provides a measurement of the network's level of service involves coordinating activities and results among many parties. Even if all parties are acting in good faith, this coordination is difficult to achieve, and the effort often produces significantly erroneous results. Erroneous results occur, for example, if network device control block counters wrap or are otherwise contaminated, if network parameters such as hop speeds are input incorrectly or if changes made to network components are not accurately recorded. Such attempts, to be at all accurate, require that all of the devices in the entire network path be known, and that access to specialized control blocks on each device be provided in order to calculate loss rates and value add network characteristics. This requirement for access to control block information is difficult to fulfill end-to-end, especially in multi-organization and in very large single organization networks, because in these environments different groups control subsets of the network and for security, privacy, and political reasons do not allow outside parties access to control block data.
As is well known among those experienced in the art, values for network speed recorded into and stored in control blocks can be incorrect as a result of faulty user input, failure to change control block contents after a configuration change (e.g., a 56 Kbps link is upgraded to 128 Kbps and the control block representing link speed is not changed), or misinformation from the link supplier (the supplier does not provide the amount of capacity in the contract, e.g., a T1 link of 1.544 Mbps comprises twenty four 64 Kbps circuits. Instances are well known in which the staff of a supplier of T1 services has failed to “turn on” all the circuits in a T1, thereby in some cases supplying as little as 64 Kbps to the customer, instead of 1.544 Mbps.)
Without an accurate measure of speed, all network measurements are suspect. For example, if the speed characterization of a network facility is inaccurate, then all calculations of utilization and loss rate will be faulty, thereby causing incorrect problem determination and capacity planning. Example: a user contracts for a 128 Kbps service from a telecommunications company (telco) supplier. Inadvertently and by accident, the supplier only provides 64 Kbps (the technician only turns on one of the two 64 Kbps channels ordered by the customer). Not knowing of the telco error, the user sets the network speed control blocks in her/his network management software to indicate that link speed is 128 Kbps. Suppose further that after customizing the network management software this way, that application traffic flows at 64 Kbps. While there is actually 100% link utilization, the network management software will report only 50% utilization (packets per second times bytes per packet times eight bits divided by 128 Kbps)=0.5=50%. At 100% utilization, the utilization causes poor response time, poor throughput, and packet loss. These symptoms often point to overutilization, but the user's network management software, faultily customized because of erroneous information provided by the telco vendor, shows no utilization problem, which will lead to fruitless examination of all of the wrong potential causes of the network problem (time wasted examining cabling, application characteristics, tuning, parameter settings, etc.) Instead of diagnosing a utilization problem and coming up with a correct solution, the user will wrongly conclude that since there is no overutilization, there must be some physical problem with hardware, or some problem with the tuning or function of software, and will spend many hours fruitlessly trying to fix the problem.
Consequently, there is a need to a system and method in which true speed, timing, and loss characteristics of a frame-relay network can be determined—not based on values supplied by a vendor, but based on analysis performed by the end user.
Generally, where there is a service level issue to be resolved across end-to-end facilities whose components are owned by more than one party, the difficulty of obtaining full cooperation end-to-end increases dramatically in comparison with environments where there is only one owner of resources.
Consequently, there is a need in the art to provide a system and method for determining an end-to-end network view of level of service that requires no special device access or cooperation among parties, especially in value add networks where the telco supplier and end users comprise a multi-owner environment.